Turbine



WITNESSES Jail. 22 1924. 1,481,321

A. T. KASLEY TURBINE Originai Filed Dec. 12 1921 INVENTOR ATTORN EY Patented Jan. 22, 19241.

EINW'EQ STA'EES PATENT ALEXANDER r. KASLEY, or ESSINGTON, rENNsv 'vANIe, essre oa ro WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION or PENN- SYLVANIA.

Original application filed December 12, 1921, Serial No. 521,872. Divided and this application filed' April 2a, 1923. Serial Na-eaaoev.

To all whom it may concern.

Be it known that I, ALEXANDER T. KAS- LEY, a citizen of the United States, and a resident of Fissington, in the county of Delaware and State of Pennsylvania, have invented a new and useful Improvement in Turbines, of which the following is a specification, this application being a division of my application Serial No. 521,872, filed December 12, 1921, the latter application being a continuation in part of my application Serial No. 546,517, filed July 21, 1921.

My invention relates to steam or elasticfiuid turbines, and more particularly to lowpressure blading of the relatively wide'type which receives steam. or elastic fluid laterally and discharges it peripherally, and it has for its object to provide low-pressure blading of this character which shall be so designed as to operate with little, if any, vibration or deformation due to centrifugal bending stresses and which shall be capable of being easily and cheaply manufactured.

A further object of my invention is to provide, in connection with bl'ading of the character designated, means which shall deflect the steam or elastic fluid from an axial toward a radial direction and which shall reinforce the blading structure.

In the drawings, forming a part of this application. Fig. 1 is a sectional view of a turbine with one form of my improved blading applied thereto; Fig. 2 is a perspective view on a large scale of one of the blades shown in Fig. 1; Figs. 3, 4: and 5 are sectional views taken along the line IIIIII, IVIV and VV, respectively, of Fig. 2; and Figs. 6 and 7 are diagrammatic views illustrative of certain features of my invention.

In the construction of steam or elasticfluid turbines, particularly of the large highspeed type, it has heretofore been found to be necessary to provide the last row or group of rows of moving blades with large leaving angles in order to handle the large volumes of low-pressure steam or elastic fluid for the reason that, for a given speed, the blade height is limited by the allowable stress of the material of which the blade is made; and. of course, as the leaving angles are made larger the efliciency of the blading dei In the construction of high-power single unit turbines, difli'cult-ies have been met with on account of excessive blade speeds due to the large rotor or disk diameter and the last row of tall moving blades necessary to pass the elastic fluid if the latter is to be discharged without too much residual energy. In the application of Henry F. Schmidt, Serial No; 482,768, filed Jul 6, 1921', and assigned to the Westinghouse lectric and Manufacturing Company, there is disclosed and claimed relatively wide lastrow 'bladin'g which discharges peripherally or peripherally and laterally, thereby making it possible to provide high po-wer turbine units without encountering excessive blade speeds.

The blatd'ing disclosed andclaimed in said application. of Henry F. Schmidt is relatively wide and it is capable of handling large volumes of low-pressure elastic fluid or steam and of discharging the latter at small angles, thereby resulting inhigh blade efficiency, in improved turbine performance, and in making it practicable to construct large, high-speed turbines which operate with high efficiency; In the Schmidt turbine, adequate discharge area" atsmall leaving angles is provided by having the steam or elastic fluid discharged peripherally'o'r' at the tips, thereby rendering it possible to make the disc-h'arge'a'rea equal at leastto the area swept'by the inlet sides of the blades merely by choosing a width of'blade which will serve this purpose.

It is characteristic of the Schmidt type of low pressure or exhaust moving blades that they are relatively much Widerthan corresponding blading of the axial-flow type. In other words, the direction of flow of steam between the-blades is changed and the steam is eitpanded and discharged peripherally so that adequate discharge area may be provided, with. the preservation of efficient dis charge anglesymerely by choosing a proper width. It will be obvious that achange in width isnotaccompanied by any change in unit stress in the blatlii'ig, whereas, with axial-flow blading, an increase in the discharge area is secured by making the blades taller or by choosing larger discharge angles. As axial-flow blading is made taller, the centrifugal stresses increase until a point is reached beyond which it is not safe to go and further discharge .area may be provided only by gauging or providing the blades with. larger discharge angles which produce less etiicient blading for the reason that the larger the discharge angle the larger becomes the axial component of the reactive effort. The capacity of axial-flow blading to handle large volumes of elastic fluid e'l'ficien tly is limited which is not true of blading of the wide type disclosed herein and in the Schmidt application aforesaid. Since width is a material factor in providing adequate discharg area with the latter type of blading, it is to be understood that the terms wide and relatively wide are used in this specification and the appended claims to designate blading of this character which differs markedly over axialflow blading heretofore used. This type of blading is also capable of converting a greater portion of the kinetic energy of the elastic fluid or steam into useful work than can be converted by blading of the ordinary type for the reason that, with the peripherally-dischlarging type of blading, the reactive force or effort is applied to portions of tlglblading moving at high effective blade spee It is the object of my invention to improve the type of low-pressure blading disclosed in the application of Henry F. Schmidt, aforesaid so that it may be more easily and cheaply made and may be of such a design as to secure better operation. The contour of my improved blade is such that it may be easily rolled or drop-forged, ora row of blades may be built up of laminae or sections and secured together in any suitable manner. Better operation is secured by so designing each blade that the center of gravity thereof falls approximately midway of the circumferential thickness thereof, whereby centrifugal bending stresses and possibly resulting deformation .or vibration of the blades are avoided.

Referring now more particularly to the drawings for a, detailed description of my invention, in Fig. 1, I show a turbine com prising a cylinder or casing 10 having bearings 11 of any suitable type for ap ropriate journal portions of the rotor 12. Xny suit-- able energy-abstracting elements are carried by the casing and rotor for abstracting energy by the expansion of steam or elastic fluid. For example, I show a stage 12 of the multi-velocity impulse type, comprising one or more nozzles 13 adapted to discharge steam or elastic fluid at high velocity into the first row of impulse blades or buckets 14 from which the steam or elastic fluid passes to the redirecting blades or vanes 15 to be redirected against the second row of impulse blades or buckets 16, followed by a series of fractional stagescomprised by the stationary and moving rows of blades 17 and 18 carried by the cylinder or casing 10 and by the rotor 12, respectively. The steam or elastic fluid undergoes pressurevelocity conversion in the nozzle or nozzles 2' 13 and the velocity energy is abstracted in two steps by the impulse blades or buckets 14: and 1(5. Thereafter, the steam is fractionally expanded in the stages comprised by the stationary and moving rows of i 19 comprising a row of guide blades 20 carried by the cylinder or casing 10 and a row of relatively wide blades 21 carried by the rotor 12.

The guide blades 20 discharge steam or elastic fluid between the blades 21 and the steam or elastic fluid is discharged from the latter peripherally or radially and laterally or axially. Each blade 21 has an inner radial or plane portion 22 having a suitable root portion 23 for attachment to the rotor 12. The radial or plane portions 22 are arranged in approximately axial planes and constitute supports for the outer curved, spoon-outline, or trough-like portions 24: constituting energy-abstracting portions for the blades. The curved, spoon-outline or trough-like portions 24 extend from the in let sides of the blades across the tops thereof, around the rear corners and thence inwardly; and as illustrated in Figs. 1 and 2, the inwardly-extending portions may merge into the inner radial portions 22, although it is to be understood that the inwardly-extending curved portion may extend inwardly to any desired extent. This form of curved, spoon-outline or trough-like construction permits of the discharge of steam or elastic fluid both peripherally and laterally at small angles.

As shown in Fig. 1, the casing 01' cylinder 10 is provided with a portion 25 which not only constitutes a support for the guide blades 20, but also serves to cover the outer portions of the inlet sides of the trough or spoon-outline portions 24 defining nozzle expanding passages between the blades, thereby preventing the cross-flow of steam or elastic fluid into the latter passages. A suitable plate 26 is secured to the rotor 12 and is arranged to cover the rear radial portions of the blades 21.

Each of the blades 21 is so designed that its center of gravity falls substantially mid way of the thickness thereof, thereby avoiding the development of centrifugal bending stresses which might tend to cause it to vibrate or be deformed.

The inlet edges 21 of the blades 21 may be suitably inclined in accordance with the blade velocity, steam or elastic fluid velocity, and the angle ci discharge of the steam or elastic fluid from the guide blades 20. See Figs. 2, 3, and 4;.

Referring to the velocity diagram shown in Fig. 6, the vector (4 represents the velocity and direction o1 discharge of motive fluid leaving the guide blades 20, the vector Z) represents the blade velocity, and'the vector 0 represents the relative velocity of the motive fluid with respect to the blades 21. The inlet side 21 should, therefore, be so curved as to be tangent to the incoming motive fluid, that is, to the vector 0. In other words, the curvature of the inlet edges of the wide blades is determined by the direction and velocity of discharge from the guide blades and by the velocity of the moving blades.

In the apparatus described high grade efficiency is maintaned by the preservation of small discharge angles. This will be apparent from diagrammatic Fig. 7, wherein the line (Z, tangent to the inner edge of the outer portion of the curved or spoon-outline portion, represents the direction of discharge of motive fluid and the line a is the tangent to the blade tip circle 7. The angle a between the lines (Z and c is the angle of discharge and it will be noted that it is relatively small.

Apparatus made in accordance with my invention operates as follows: Steam or elastic fluid is expanded in the higher pressure stages of the turbine and it is discharged therefrom into the last low-pressure stage 19, having the relatively wide moving row of reaction blading which receives the steam or elastic fluid flowing in substantially an axial direction and discharges it peripherally or in a radial direction or peripherally and laterally. The steam or elastic fluid is expanded and discharged trom the nozzle passages, defined by the curved, spoon-outline, or trough-like portions oi the wide blades, at small angles, the feature of discharging at small angles being possible due to the tact that the discharge area may be made suflicient merely by choosing a suitable width of blade.

It will be obvious to those skilled in the art that my new type of blade is capable of securing better turbine. operation. My new blades are capable of handling large volumes of low pressure, elastic fluid or steam, of expanding the elastic fluid or steam to low pressures, of operating at high blade etiiciency as the elastic fluid or steam is discharged at small angles and the reactive effort of the high velocity elastic fluid or steam is applied to the blade portions moving at high 'eflective speeds, and of operating high speeds as the discharge area is secured by increasing the blade width instead of height. By using my wide exhaust blading, it is therefore possible to construct large, high-speed turbine units and units which operate more efficiently than heretofore.

While I have shown my invention in a single term, it will. be obvious to those skilled in the art that it is not so limited, but is susceptible oi various other changes and modifications without departing from the spirit'thereol, and I desire, therefore, that only thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

hat I claim is:

1. In an elastic-fluid turbine, a row of peripherally-discharging moving blades having lateral inlet edges which are substantially tangential to the direction of incoming elastic fluid.

2. In an elastic-fluid turbine, a low-pressure stage including a last row of moving reaction blades having inner radial and outer curved portions adapted to receive elastic fluid axially and to expand and discharge it peripherally and laterally and means for blocking the inner portions of the outer radial edges of the blades.

8. In an elastic-fluid turbine, a low-pressure stage including a last row of relatively wide moving blades adapted to receive elastic fluid axially and to discharge it periph erally, and means for blocking the inner portions of the outer radial edges of the blades.

4. In an elastic-fluid turbine, a row of blades adapted to receive elastic fluid at one side and comprising inner substantially plane portions and curved energy-abstracting portions at the tips and at the other side.

5. A turbine blade comprising an inner substantially plane portion and a curved energy-abstracting portion at the tip and at one side.

6. In an elastic-fluid turbine, a low-pressure stage including'a last row of relatively wide blades adapted to receive elastic fluid axially and to discharge it peripherally, each of said blades having an inner radial portion and peripheral and partial side trough portions, and blocking means cooperating with the outer radial side portions of the blades to assure the passage of elastic fluid between the trough portions.

7. In an elastic-fluid turbine having a casing, a rotor, and a plurality of stages carried thereby, a last-stage, including a last row of moving blades carried by the rotor, said moving blades having radial body portions and being curved peripherally and at the outer side portions and defining passages for the expansion of elastic fluid, whereby elastic fluid may be received axially and expanded peripherally and sidewise and the resulting velocity energy act reactively both upon the such limitations shall be placed peripheral and upon the side portions of the blades.

8. In an elastic-fluid turbine, a last row of moving reaction blades each having an inner radial portion and an outer spoonoutline or trough-like portion merging into a side spoon-outline or trough-like portion, the spoon-outline or trough-like portion diminishing inwardly radially and merging into said radial portion.

9. A turbine blade of the reaction type having an inclined radial inlet edge and an inner radial portion bounded, in part, by a spoon-outline or trough-like portion extending from the inlet radial edge and diminishing at the outer radial edge and merging into the radial portion.

10. In an elastic-fluid turbine, a last row of moving reaction blades, each comprising an inner radial portion bounded, in part, by an outer spoon-outline or trough-like portion extending from the inlet radial edge and diminishing inwardly radially at the outer radial edge and merging into the radial'portion, and means for blocking the outer radial portions of said blades.

11. In an elastic-fluid turbine, a last row of moving blades, each comprising an inner radial portion and an outer spoon-outline or trouglrlike portion extending from the inlet radial edge and diminishing inwardly radially at the outer radial edge and merging into the radial portion, the outer portions of the spoon-outline or trough-like portions defining passageways for the expansion of elastic fluid peripherally and sidewise, and means for blocking the outer edges of the radial portions of the blades.

In testimony whereof, I have hereunto subscribed my name this nineteenth day of April, 1923.

ALEXANDER T. KASLEY. 

